Once in a blue moon: Stunning pictures from around the world

Some of the best views of the blue moon were in the United States, including views of the Statue of Liberty. A 'blue moon' is when there are two full moons in a calendar month and the next one will be in 2018 -- hence the phrase "once in a blue moon".

A truly blue coloured moon can occur on rare occasions, according to NASA, with most being spotted after volcanic eruptions.

A blue moon rises over the scoreboard during the sixth inning in a game between the Chicago White Sox and the New York YankeesGettyThe Eurotunnel terminal is illuminated by a rare blue moon on July 31, 2015 in Folkestone, England. Hundreds of migrants are continuing to attempt to enter the Channel Tunnel in Calais, France and onto trains heading to the United KingdomGettyThe so-called blue moon is seen above Washington on 31 July, 2015. The blue moon is the second appearance of a full moon in the same calendar month. The next blue moon will not be seen until January 2018GettyThe Statue of Liberty in New York pictured with the Blue MoonReutersA full moon rises behind a telecommunication tower over the Camlica Hill in Istanbul, TurkeyReutersThe statue of the angel on the top of Castel Sant'Angelo is seen past a full moon in Rome, ItalyReutersA full moon over north LondonReutersThe view over Loosely Row, near Princes Risborough, southeast EnglandReutersA cyclist rides his mountain bike as the Blue Moon rises in a park in Rome, ItalyReuters